Lighting : By Two Halves Or All At Once

[dazbud]

Hi all
 
just upgraded to my new 250L tank. Loving it already.
 
I'v always had live plants and had relatively good success on my old 100L tank with just 6 hours of single T5 light (27W for 100L, which is nearly 0.27W/ltr ). No CO2, although continuous airstone. Low light planting. 
 
My new tank offers more choice. It comes with 3x39W, one pink and two white. Switches allow all three on at once, or the two white or the one pink.
 
I'd like to continue keeping live plants, although the tank is a little deeper at 23" as opposed to my previous 15". Obviously with all three on, I'm getting more wattage than I did before, ie 0.47W/Ltr). So if the plants did OK before I'm execting them to do OK again now with the expense and hassle of CO2injection.
 
However, I have what might seem a silly question .... When I'm in the room, I actually just prefer the pink light on. The fish look nicer and it suits the ambience of the room better. Is it essential to have all three bulbs on for my planned 6 hours to get most benefit for the plants, or could I have the two white on for 6 hours and then the one pink on for 6 hours and get the same growth benefit?


meant to say, without CO2. I don't really want to start over complicating things

 

[techen]

Using CO2 is very very easy to do, That said I wouldn't say you're lighting is all that powerful anyway and CO2 wouldn't really matter.
 
The two white lights are important for plant growth, The pink one is really just to bring out the colours in the fish as well as the aid plant growth too. So running all 3 is pretty much needed if you want some nice healthy plant growth.